Multi-functional lubricating oil additives



MULTI-FUNCTIONAL LUBRECATING OIL ADDITIVES James R. Roach, Beacon, andJohn R. Morris, Fishkill, N. Y., assignors to The Texas Company, NewYork, N. Y., a corporation of Delaware No Drawing. Application May 13,1955 Serial No. 508,306

2 Claims. (Cl. 252-336) This invention relates to novel multi-functionallubricating oil additives. More particularly, this invention relates tolubricating oil additives which act as detergents, anti-oxidants andanti-corrosives.

We have found that minor amounts of divalent metal salts ofN,N-dialiphatic dithiocarbamyl aliphatic carboxylic acids having thefollowing general formula [R NCSS CH COOhZ wherein R represents analiphatic hydrocarbon radical, x is at least 1 and Z represents adivalent metal, are excellent lube oil additives and act asanti-oxidants, anticorrosives and detergents. The useful addition rangeof these compounds in a lube oil is from about 0.2 to 2.0% by weight;however, the preferred concentration is about 1%.

Examples of divalent metals which are used in the formation of the saltsof N,N-dialiphatic dithiocarbamyl aliphatic carboxylic acids aremagnesium, zinc, barium,

calcium, tin and strontium. Of these, the magnesium saltN,N-di-2-ethylhexyl dithiocarbamyl propionate, tin N,N

diamyl dithiocarbamyl acetate, zinc N,N-dibutyl dithiocarbamyl acetate,zinc N,N-dioctyl dithiocarbamyl acetate, strontium N,N-dioctyldithiocarbamyl acetate, calcium N,N-dioctyl dithiocarbamyl acetate,calcium N-amyl N-octyl dithiocarbamyl acetate, calciumN,N-di-2-ethylhexyl dithiocarbamyl butanoate, calcium N,N-dibutyldithiocarbamyl steal-ate, zinc N,N-di-3-hexyldecyl dithiocarbamyloleate, magnesium N-butyl N-2-ethyl-4-hexyldecyl thiocarbamyl acetateand magnesium N,N-di-2-methyl-4- butyldecyl thiocarbamyl acetate.

From the above examples it is apparent that the x in the general formula[R NCSS(CH ),,COO] Z can denote an integer from 1 to 20. However,acetates wherein x is l are the preferred class of compound on the basisof availability and cost. The aliphatic radicals on the nitrogen atommay contain 4 to but usually have 6 to 12 carbon atoms.

We have also found that combinations of divalent metal salts ofN,N-dialiphatic dithiocarbamyl aliphatic carboxylic acids with the wellknown metal phenolate type detergents such as metal alkyl phenolates,metal alkyl salicylates, metal alkyl phenolate-sulfonates, metal alkylphenolate-sulfides and disulfides serve as multifunctional lube oiladditives having excellent detergent,

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anti-corrosive and anti-oxidant properties. The metals which are usefulin forming these detergents are magnesium, zinc, barium and calcium. Thealkyl group in these metal phenolates ranges from 4 to 30 carbon atoms.

The amount of these detergents which we have found to be useful in thecombination, ranges from about 25 to 75% by weight of the divalent metalsalt of the N,N- dialiphatic dithiocarbamyl aliphatic carboxylic acidbut we prefer from about 25 to of the detergent in the mixture prior toits addition to the lube oil.

The combination additive comprising a divalent metal salt of anN,N-dialiphatic dithiocarbamyl aliphatic car: boxylic acid and adetergent from the above mentioned group is used in lube oils in aconcentration range from about 0.5 to 2.5% by weight with about 1.5%preferred. Specific examples of salt-detergent combinations with theirpercentage composition are as follows: Magnesium N,N-di-2-ethylhexyldithiocarbamyl acetate 67% and zinc alkyl salicylate 33% wherein thealkyl group comprises olefin polymers having an average of 25 carbonatoms; magnesium N-amyl N-octyl dithiocarbamyl propionate 75% and bariumhexyl phenolate 25%; magnesium N,N-dioctyl dithiocarbamyl acetate andzinc lauryl phenolate 40%; magnesium. N,N-dioctyl dithiocarbamyl acetateand calcium hexyl phenolate sulfonate 35%; calcium N,N-dioctyldithiocarbamyl acetate and zinc alkyl salicylate 30% wherein the alkylgroup comprises olefin polymers having an average of 20 carbon atoms;and zinc N,N-dibutyl dithiocarbamyl laurate 63% and barium alkylphenolate 37% wherein the alkyl group comprises olefin polymers havingan average of 15 carbon atoms.

The salts of the N,N-dia1iphatic dithiocarbamyl aliphatic carboxylicacids useful in the present invention may be formed by variousreactions. One such method is given in the following example .todemonstrate the formation of the magnesium salt of N,N-di-2-ethylhexy1dithiocarbamyl acetic acid.

EXAMPLE 1 One mol of KOH in the water solution was added to 1 mol of CSwhile the temperature was maintained at 18-20" C. One mole ofdi-2-ethylhexyl amine was added to this drop-wise while maintaining thetemperature at 1820 C. After all the amine was added, the

reaction product was allowed to warm to room tempera ture while stirringcontinuously. Water and excess CS were removed by vacuum means leaving aheavy viscous amber liquid which waspotassium N,N-di-2-ethylhexyldithiocarbamate. I

One mol of bromoacetic acid was dissolved in 200 ml. of ethanol. Tendrops of phenolphthalein was added to this and thereafter, KOH which hadpreviously been dis solved in ethanol was added drop by drop to thebromoacetic acid solution until the first faint pink color was obtaineddesignating the formation of potassium bromoacetate. H

One mol of the previously formed potassium N,N- di- 2-ethylhexyldithiocarbamate was mixed with ethanol to form a solution and potassiumbromoacetate was added slowly thereto. This was stirred for 5 hours atroom temperature, acidified with HCl, water added and then extractedwith ether. The extract was water-washed until free from acid, the etherwas evaporated, benzene added and the washings were dried under reflux.The benzene was stripped off under reduced pressure andN,N-di-2-ethylhexyl dithiocarbamyl acetic acid was obtained as a darkamber red clear liquid. This was dis solved in dry toluene and warmed to40-50 C. Magnesium methylate in an amount sufiicient to react with theentire amount of the N,N-di-2'-ethylhexy1 dithio- 3 carbamyl acetic acidwas was heated to reflux and the methanol formed in the reactionremoved. The solvent was stripped off under reduced pressure and 245 g.of 300 Pale Oil was added. This was then stripped for about 2 hours on avacuum pumpat 110 C. The resulting product is magnesiumN,N-di-2-ethylhexyl dithiocarbamyl acetate.

Lubricating oils used in the instant invention are mineral lubricatingoils of the naphthene distillate, paratfin distillate, mixed paraflinand naphthene distillate type and residual oils having a viscosity rangefrom about 70 to 1400 SSU at 100 F. The preferred lube oils are furfuralrefined, solvent dewaxed paratfin base distillates having a viscosity of540-600 SSU at 100 F.

The following table shows the results of bench tests using a base oilwhich was a furfural refined, solvent dewaxed, parafiin base distillatetype mineral oil having a viscosity of 560 SSU at 100 F.; a flash of 465F.; a pour of +5 F. and a V. I. of 92, and having 1% by weight ofmagnesium di-Z-ethylhexyl dithiocarbamyl acetate incorporated therein.

The above tests are either well known or modifications of well knownbench tests designed to preview characteristics of lubricant additivesprior to engine testing. The MacCoull-Scholp corrosion test is similarto the well known MacCoull corrosion test and is further described in U.S. Patent 2,674,577 to Frederic C. McCoy, Bill L. Benge, Edwin C.Knowles and Chas. C. Towne, issued April 6, 1954. The Beacon-Penn. Stateoxidation test is a simplified small scale Penn. State oxidation testwhich has been primarily achieved by combining the ballast reservoir andoxygen burette into one vessel. The upper half of the vessel serves asthe ballast reservoir, and

the lower half as the calibrated burette. The change facilitated thedesign of a more compact unit and eliminated the pressure andtemperature controls for one chamber. Except for some other minormodifications in design, the other basic features of the small scalePenn. State oxidation test are maintained.

We have subjected the additives of the instant invention to a Lauson L-4engine test, the results of which follow. This test was performed on ablend of 50% by weight of a furfural refined, solvent dewaxed, parafiinbase distillate type oil having an SSU viscosity of 153 at 100 F.; aflash of 400 F.; a pour of -l0 F. and a V. I. of 98.5, and 47.5% of anairplane engine oil comprising a highly refined residuum from paraflinadded slowly. The product base crude oil, having an SUS viscosity of1693 at R; a flash of 555 F.; a pour of +l5 F. and a V. I. of 96.2. Theblend had 2.5% of magnesium N,N-di-2- ethylhexyl dithiocarbamyl acetateincorporated therein.

Table 2 2.5% Add1- tlve Base 011 Base Oil Luuson L-l Test: Bearing Wt.Loss .mg 57 892-383 Table 3 1.5% Add!- time Base 011 Base 011 Lauson L-4Test:

Bearing Wt. Loss .mg 138 333-380 Piston Rating 8.3 7. o

The results shown in the foregoing tables thoroughly demonstrate theefiectiveness of our invention as a multifunctional additive for lubeoils either utilizing the salt of aliphatic dithiocarbamyl aliphaticcarboxylic acid alone or in combination with a detergent.

Obviously, many modifications and variations of the invention, ashereinbefore set forth, may be made without departing from the spiritand scope thereof and, therefore, only such limitations should beimposed as are indicated in the appended claims.

We claim:

1. A lubricant composition comprising a major'proportion of a minerallubricating oil and betweenl and 2 percent by weight of a mixture ofabout 2, parts of the magnesium salt of N,N-l-dialkyl dithiocarbamylacetic acid wherein said alkyl group has from 4 to 12 carbon atoms, andabout 1 part of zinc alkyl salicylate wherein said alkyl group has anaverage of from 20 to 30 carbon atoms.

2. A lubricant composition comprising a major proportion of a minerallubricating oil and about 1.5 percent by weight of a mixture of about 2parts of the magnesium salt of N,N-di-2-ethylhexyl dithiocarbamyl aceticacid and one part of zinc alkyl salicylate wherein said alkyl group hasan average of 25 carbon atoms.

Harle Dec. 2, 1952 Karll Nov. 2, 1954 U S DEPARTMENT OF COMMERCE PATENTOFFICE CERTIFICATE OF CORRECTION Patent No. 2,832,737 James R. Roach eta1. April 29, 1958 It is hereby certified that error appears in theprinted specification of the above numbered patent requiring correctionand that the said Let cers Patent should read as corrected below.

Column 4, line 48, for "magnesium salt of N,Nl-dialkyl dithiocarbamylacetic read magnesium salt of N ,N-dialkyl dithiocarbamyl acetic Signedand sealed this 17th day of June 1958.

(SEAL) Attest:

KARL AXLINE ROBERT c. WATSON Attesting Officer Conmissioner of Patents

1. A LUBRICANT COMPOSITION COMPRISING A MAJOR PROPORTION OF A MINERALLUBRICATING OIL AND BETWEEN 2 AND 2 PERCENT BY WEIGHT OF A MIXTURE OFABOUT 2 PARTS OF THE MAGNESIUM SALT OF N,N-1-DIALKYL DITHIOCARBAMYLACETIC ACID WHEREIN SAID ALKYL GROUP HAS FROM 4 TO 12 CARBON ATOMS, ANDABOUT 1 PART OF ZINC ALKYL SALICYLATE WHEREIN SAID ALKYL GROUP HAS AAVERAGE OF FROM 20 TO 30 CARBON ATOMS.